Friday, April 30, 1999 Published at 01:20 GMT 02:20 UKWorld: AmericasUS: Nuclear secrets leak top priorityThe leaked information could accelerate China's nuclear weapons programmeInvestigating the theft of 50 years of US nuclear research is the Federal Bureau of Investigation's top priority, a senator said on Thursday.

"The FBI director did tell us that the espionage in our labs is the highest priority that the FBI has in America today," said Senator Richard Shelby, Head of the Senate Intelligence Committee, after a three-hour hearing from Mr Freeh.

The United States is investigating allegations that a physicist who worked at one of its weapons labs, Wen Ho Lee, handed over the blueprint for the US nuclear weapons programme to the Chinese government.

"As the investigation is unfolding, it's confirming some of
their (FBI's) worst fears" about how much information China
probably has, said Mr Shelby.

"They (FBI) don't know how deep and wide
it is at this point, but it's bad."

The Chinese government denies that it took the information.

The Taiwan-born physicist worked at Los Alamos, America's main nuclear research laboratory.

Between 1993 and 1995, the FBI has discovered that he transferred millions of top secret files from secure, classified computer to an unclassified system that could be accessed from outside of the lab.

They were accessed by someone, but the FBI will not say who.

US Energy Secretary Bill Richardson said the data transfer was "a serious security breach that is unconscionable."

'China modernising nuclear arsenal'

The scientist was fired on 8 March for security violations, but he had been under investigation by the FBI for three years.

"The Chinese are now modernising their nuclear arsenal. They are still at a fairly early stage. This is exactly what they need to get them to the point where we are," said Dr Gary Milhollin, Director of the Wisconsin Project in Nuclear Arms Control in Washington.

These codes represent 50 years of American nuclear weapons research.

China could pass them along to Russia or even Pakistan, BBC Correspondent Tom Carver said.